ERBB2 and neoplasm: Of the 139 patients with pre-treatment HER2-positive tumours (IHC 3+ or IHC 2+/HER2 amplified), 31 tumours (22.3%) become HER2-negative (IHC 2+/HER2 non-amplified, or IHC 0/1+) after treatment, whereas 13/82 (15.9%) of patients with HER2-negative tumours before treatment changed to HER2-positive following treatment (p = 0.01).